Meta-3-alkoxyureidophenyl N-haloalkyl carbamates as herbicides

ABSTRACT

New m-(3-alkoxyureido and 3-alkoxythioureido)phenyl carbamates wherein at least one valence of the carbamate nitrogen is satisfied by a halogen-substituted lower alkyl group are shown to be selective herbicides.

United States Patent [191 Dorschner et al.

META-3-ALKOXYUREIDOPHENYL N-HALOALKYL CARBAMATES AS HERBICIDES Inventors: Kenneth P. Dorschner; James A.

Albright, both of Jacksonville, Fla.

Assignee: SCM Corporation, New York, NY.

Filed: Jan. 28, 1974 Appl. No.2 436,909

Related U.S. Application Data Division of Ser. No. 211,111, Dec. 22, 1971, Pat. No. 3,806,536.

U.S. Cl 71/106; 71/99 Int. Cl A0ln 9/24 Field of Search 71/106, 99

References Cited UNITED STATES PATENTS 12/1969 Tilles et a1. 71/100 Primary ExaminerGlennon H. Hollrah Attorney, Agent, or Firm-A. Joseph Gibbons; Merton H. Douthitt [57] ABSTRACT New m-(3-alkoxyureido and 3-alkoxythioureido)phenyl carbamates wherein at least one valence of the carbamate nitrogen is satisfied by a halogensubstituted lower alkyl group are shown to be selective herbicides.

5 Claims, No Drawings META-3-ALKOXYUREIDOPHENYL N-HALOALKYL CARBAMATES AS HERBICIDES This is a division of application Ser. No. 211,] ll, filed Dec. 22, 1971, now U.S. Pat. No. 3,806,536.

BACKGROUND OF THE INVENTION U.S. Pat. No. 3,547,979 is believed to show compounds which are the closest analogs to those of the instant invention. The compounds of that patent are alkylcarbamoyloxyphenyl N-alkoxyureas and are described as useful weed killers. Our co-pending application entitled Meta Ureidophenyl N-I-laloalkyl Carbamates also teaches close analogs as selectively effective herbicides. Additional generally relevant but more remote art known to applicants is listed in the attachment to this application.

It has been found that a minor modification of one substituent radical satisfying a valence of the carbamate nitrogen of the foregoing carbamoyloxyphenyl N- alkoxyureas provides the crop grower with a selective herbicide, i.e. a compound or composition which will kill or stunt the growth of weeds in a germinating or growing crop without harming the plant crop beyond the point of recovery.

BRIEF SUMMARY OF THE INVENTION DETAILED DESCRIPTION OF THE INVENTION The novel 3-alkoxylatedureidophenyl carbamates of this invention include the corresponding thioureido and thiocarbamate derivatives characterised in that at least one of the valences of the carbamate nitrogen is satisfied by a halogen-substituted lower alkyl group and the second valence is satisfied by either hydrogen, a

lower alkyl group or by a halogen-substituted lower alkyl group depicted generally as:

Wherein X and X represent either oxygen or sulfur; R and R are the same or different lower alkyl groups, R; is a lower alkyl group or hydrogen, R is a lower alkyl group, hydrogen or a halogen-substituted lower alkyl group and R is a halogen-substituted lower alkyl group. Unless otherwise defined, lower alkyl group signifies a straight or branched chain alkyl group of l to 6 carbon atoms.

Of the above illustrated 3-alkoxylatedureidophenyl carbamates the compounds where R and R are hydrogen and R is methyl appears to be the most effective and economical. Surprisingly, the novel compounds of this invention have been found to control selectively undesired weeds when used as pre-plant, pre-emergent and post-emergent herbicides for crop plants, in contrast to the close analogs of US Pat. No. 3,434,822 and specifically U.S. Pat. No. 3,547,979 which are generally used for complete eradication of weed species or in some cases for an after-harvest treatment control of weeds in the subsequently planted crop. It was not anticipated that this pre-planting type herbicide could be easily modified by replacing the tertiary butyl group or lower alkyl group with a halogen-substituted lower alkyl group to produce a truly effective selective herbicide that would find use as post-emergence herbicides.

The novel compounds of this invention may be prepared by general methods described in the literature for the synthesis of 3alkoxylatedureidophenyl carbamates. One method is to first prepare the maminophenyl haloalkyl carbamate and react it with phosgene to produce the corresponding isocyanate which is then further reacted with the appropriate N,O-dialkylhydroxylarnine to give the desired metaalkoxyureidophenyl haloalkyl carbamate. Other methods known in the art may be used but attention must be given in any particular synthesis to protect reactive groups and to prevent undesired side reactions from taking place. In addition to the sensitive alkoxy groups on the urea portion of the molecule some precaution must be taken to prevent possible quaternization reactions which can take place between a halide and a tertiary amine. Other synthetic approaches may involve the reverse preparation where the l-alkoxy-3-(mhydroxyphenyl) urea is first prepared and then reacted with the desired haloalkyl isocyanate.

Examples of halogen-substituted lower alkyl groups of l to 6 carbon atoms on the carbamate nitrogen include methyl, ethyl, n-propyl, isopropyl, butyl, n-butyl, sec-butyl, tert-butyl, pentyl and hexyl groups and the like. Halogen atom substitution can be at any of the carbons of such alkyl group, but compounds of this type where the halogen is on terminal carbon atoms are preferred because of their availability and because they have been found especially effective. Plural halogen substitution on the same or different carbon atoms is possible. The halogen atom substituent can be chlorine,

iodine, bromine or fluorine, but is preferably chlorine since the chloroalkyls are highly effective and economical to prepare. When R R R and R in the above formula represent lower alkyl groups, methyl and ethyl groups are generally preferred because of their economy.

Specific compounds illustrative of the formula which are very effective and selective in eliminating and controlling weeds including mustard (Brassica spp.), coffee weed (Sesbania spp.), pigweed (Amaranthus spp.), crabgrass (Digitaria spp.), barnyardgrass (Echinochloa spp.), giant foxtail (Sezaria spp.) annual morningglory (Ipomoea spp.), Texas Panicum (Panicum texanum), and the like without significant injury to the specific crops such as rice, corn, cotton, peanuts and soybeans are as follows:

chloropropyl) carbamate O-[ m-( 3-Methoxy-3-methylureido )phenyl] N-( 4- chlorobutyl) carbamate O-[m-( 3-Methoxy-3-methylureido )phenyl] N-( 2- trifluoroethyl) carbamate preferred. it is desirable that both the inert carrier and herbicide, if solids, be ball-milled or ground by other common techniques to a very fine state of subdivision so that they will pass through a 325-mesh screen (U.S.

O-[m-(3-Methoxyureido)phenyl] N-(Z-chloroethyl) 5 Standard carbamate The formulation can contain various other agents to O-[m-(3-Methoxyureido)pheny]] N-( 3 fl o l) wet, disperse, and emulsify the herbicidal composition carbamate whether or not a solvent is used in the application to O (3 M th id h l1 N413- the locus of the plant or to the soil. The surfactants or dichloropropyl) carb at other detergents employed can be anionic, nonionic, or S-[m-(3-Methoxy-3-methylureido)phenyl] N (2 cationic as are detailed in McCutcheons 1969 publicachloroethyl) thiocarbamate tion on Detergents and Emulslfiers. Surfactants useful S-[m-(3-Methoxy-3-methylureido)phenyl] N-(3- in formulation of our selective herbicides, are usually chloropropyl) thiocarbamate added in amounts of 1 to 10 percent based on the total O-[m-(3-Methoxy-3-methylureido)phenyl] N-(Z- 5 weight of wettable powder formulation but generally in chloropropyl) thiocarbamate the order of 2 percent. These can be alkyl and alkylaryl O-[m-(3-Methoxy-3-methylureido)phenyl] N-(3- polyether alchols, polyoxy ethylene sorbitols, or sorbichloropropyl) thiocarbamate tan fatty acid esters, alkylaryl surfonates, long chain quaternary ammonium chlorides, and the like. Pre- The compounds of this invention can also be named ferred surfactants are the fatty esters of inorganic salts as carbamic acids, esters with various ureas or as carbaof isethionic acid and especially preferred is the oleic mates according to the IUPAC Rules, examples of ester of sodium isethionate. which would be: The compounds of this invention are best applied as herbicides as a broadcast treatment whereby the com- (Z-Chloroethyl) carbamic acid, ester with 3-(mpound is emulsified in water or as a wettable powder hydroxyphenyl)-l-methoxy-l-methylurea or formulated with wetting agents and applied as an aquem(3 -Methoxy-3-methylureido)phenyl (2-chloroethyl) ous Spray over the entire area of land, which can inarbamate clude the crop plant. Water emulsions may be prepared with the aid of emulsifiers such as triethanol amine stearate, sodium lauryl sulfonate, sodium alkyl naphtha- B y crop plants 15 generally meant agricultural crops lene sulfonate, Sodium Oleate p winch used for food supPly of man and ammals but octylphenoxypolyethoxy ethanol, as well as other wellthis also includes other desirable plants such as grass known emulsififlg Similarly, these herbicides can be and grass Species where broadleaved and grassy applied as a pre-plant treatment to the area before the undeislrable weeds are to be Controlled Suppressed or crop or weeds emerge from the soil. In this case, applieradlcated' cation is made after planting the crops. The compounds Although climatic and soil conditions dictate the def thi invention, as shown in the Examples, can be efsirable application rate of these N-halogen-substituted fectively used by either of the above treatments, but are alkyl carbamates, they are generally used from about 43 especially beneficial as post-emergent treatment when to about 8 pounds per acre based on the weight of th application is made after the emergence of a particular N-haloalkyl carbamate in the composition. Amounts crop or weed. The characteristic of a good selective smaller than /8 and amounts greater than 8 pounds per herbicide is that when it is applied near or on the foacre can be utilized, depending on the crop to be proliage of the crop plant, only the weed species is killed tected, the location, and the undesirable weed species while the valuable crop plants are not harmed beyond to be killed. Conventional formulations can be used to 45 the point of recovery, thus allowing a high percentage apply these herbicides but applications as wettable (80-100 percent) to mature to harvestable crops. In powders dispersed in an aqueous medium are preferred this respect the compounds of this invention differ conwhen the carbamate is relatively insoluble in the applisiderably from the 3-alkoxylatedureidophenyl carbacation solvent. Wettable powders can be formulated mates of the prior art which generally were found to be from inert carriers such as clays, talc, diatomaceous non-selective herbicides useful as soil sterilants and earth and other siliceous inorganic solids and silicates. post-harvest herbicidal treatments for subsequent Although the wettable powder can contain any proporplanting as shown in U.S Pat. No. 3,547,979. tion of active herbicide from I to 98 percent, it is gen- The following examples are intended to illustrate the erally more economically feasible to use a high loading invention but not to limit the scope thereof, parts and of active selective herbicide material. Active ingredient percentages being by weight unless otherwise specified. concentrations of 509O percent based on weight of EXAMPLE 1 inert carrier 18 recommended, and concentrations in the order of weight percent active ingredient are Meta aminophenyl N-2-chloroethylcarbamate no au sntoAd 2 o c1cH cH N=c=o-) E z NH2 0 2 @-o-NH-cH cH c1 (Pd/c) When the compound of Example 2, wettablc powder; is applied toyarious plant foliage as To 139 parts meta nitrophenol in 600 parts tetrahydrofuran is added with stirring 106 parts 2- chloroethylisocyanate using 5 ml dibutyltin diaeetate catalyst. After standing four hours the mixture is poured into a beaker containing 600 parts ice and is neutralized with 0.2N sodium hydroxide solution. The resulting m-nitrophenyl N-Z-chloroethylcarbamate is collected, washed with ice water. and dried. I

24.4 parts meta-nitrophenyl N-Z-chloroethylcarbamate dissolved in 100 parts ethylacetate is hydrogenated in a Paar hydrogenation apparatus using 2.5 parts palladium on carbon catalyst until the hydrogen is no longer absorbed. After degassing with nitrogen the catalyst is filtered and the solvent is removed under reduced pressure. The residue is essentially maminophenyl N-Z-chloroethylcarbamate.

EXAMPLE 2 O-[m-( 3-methoxy-3-methylureido )phenyl] N-( 2-chloroethyl) carbamate To 215 parts meta aminophenyl N-(Z-chloroethyl) carbamate in 400 parts l.2-dimethoxyethane is added 107 parts N-Methoxy-N-methyl carbamyl chloride while stirring magnetically at room temperature and the resulting mixture is allowed to stand for several hours before separating the above identified curb-amate.

EXAMPLE 3 O-[m-( 3-methoxy-3-methylureido )phenyl] N-( 3-chloropropyl) carbamate 229 parts meta-aminophenyl N-3-chloropropyl carbamate. prepared in a manner similar to that shown in Example 1 except that 3-chloropropyl isocyanate is used in place of Z-chloroethylisocyanate is dissolved in 400 parts tetrahydrofunm containing 202 parts triethylamine and added dropwise to a solution of 98 parts phosgene dissolved in 500 parts tetrahydrofuran while carefully maintaining the temperature below [0C. After completion ofthe reaction. the-mixture is filtered to remove triethylamine hydrochloride and the filtrate is evaporated to yield O-l m-( 3-methoxy-3- methylureido )phcnyl] N- 3-chloropropyl) carbamate.

EXAMPLE 4 formulated as a an aqueous spray at the rate of 1.5 pounds active ingredient per acre, and the plants are inspected 21 days later. peanut plants will exhibit no apparent injury whereas mustard coffeeweed, and barnyard-grass are 5 killed. Selectivity in favor of growing rice corn (maize) and cotton while suppressing one or more of such pest weeds is expected also. What is claimed is: l. A herbicidally effective composition comprising M an inert carrier and 1-98?! of a carbamate of the forwherein X represents either oxygen or sulfur; R and R are the same or different lower alkyl groups, R;, is a lower alkyl group or hydrogen. R is a lower alkyl group, hydrogen or a halogen-substituted lower alkyl group and R is a halogen-substituted lower alkyl group.

2. A process for protecting crop plants from undesirable weed growth which comprises applying to the locus thereof a selectively effective herbicidal amount of a carbamate of the formula:

5 v N R5 wherein X represents either oxygen or sulfur; R, and

R are the same or different lower alkyl groups. R is a lower alkyl group or hydrogen. R is a lower alkyl- 

1. A HERBICIDALLY EFFECTIVE COMPOSITION COMPRISING AN INERT CARRIER AND 1-98% OF A CARBAMATE OF THE FORMULA:
 2. A process for protecting crop plants from undesirable weed growth which comprises applying to the locus thereof a selectively effective herbicidal amount of a carbamate of the formula:
 3. The process of claim 2 wherein R4 is hydrogen and R5 is a chlorinated or brominated alkyl.
 4. The process of claim 3 wherein the carbamate is O-(m-3-methoxy-3-methylureido)phenyl) N-(3-chloropropyl) carbamate.
 5. The process of claim 3 wherein the carbamate is O-(m-(3-methoxy-3-methylureido)phenyl) N-(2-chloroethyl) carbamate. 